#game{
    position: relative;
    width: 100%;
    height: 600px;
    background-image: url('../images/sky.png');
}
.bird{
    position:absolute;
    top: 235px;
    left: 50%;
    margin-left: -15px;
    width: 30px;
    height: 30px;
    background-image: url('../images/birds.png');
    transition: top .3s linear;
}
.start{
    cursor: pointer;
    position: absolute;
    top: 295px;
    left: 50%;
    margin-left: -100px;
    width: 200px;
    height: 60px;
    line-height: 60px;
    text-align: center;
    transition: all .3s linear;
    font-weight: bolder;
}
.start.start-white{
    color: white;
    font-size: 24px;
}
.start.start-blue{
    color: #09f;
    font-size: 36px;
}
.score{
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    font-size: 24px;
    color: #fff;
    font-weight: bolder;
    display: none;
}
.mask{
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #000;
    opacity: .7;
    display: none;
    z-index: 2;
}
.end{
    position: absolute;
    top: 70px;
    left: 50%;
    transform: translateX(-50%);
    text-align: center;
    display: none;
    z-index: 3;
}
.end .over{
    font-size: 35px;
    font-weight: bolder;
    color: red;
}
.end .result,
.end .final-score{
    margin-top: 20px;
    color: #ff0;
    font-size: 20px;
    font-weight: bold;
}
.end .rank-list{
    margin-top: 20px;
    color: #09f;
    text-align: left;
}
.end .rank-item{
    height: 30px;
    line-height: 30px;
    margin-bottom: 10px;
    padding: 0 10px;
    font-size: 13px;
}
.end .rank-degree{
    display: inline-block;
    width: 14px;
    height: 14px;
    line-height: 14px;
    margin-right: 10px;
    text-align: center;
    color: #fff;
    background-color: #8eb9f5;
    font-size: 12px;
}
.end .rank-degree.first{
    background-color: #f54545;
}
.end .rank-degree.second{
    background-color: #ff8547;
}
.end .rank-degree.first{
    background-color: #ffac38;
}
.end .rank-score{
    display: inline-block;
    width: 30px;
}
.end .restart{
    color: #09f;
    font-size: 18px;
    font-weight: bolder;
    cursor: pointer;
}
.pipe{
    position: absolute;
    width: 52px;
    height: 150px;
    z-index: 1;
}
.pipe.pipe-up{
    top: 0;
    background-image: url('../images/pipe2.png');
    background-position-y: bottom;
}
.pipe.pipe-bottom{
    bottom: 0;
    background-image: url('../images/pipe1.png');
}